Magnet valve device



D. L. MCNEAL.

MAGNET VALVE DEVICE Filed April 16, 1938 Il l lNvENToR DDNALD l.. McNEAl.

Mya@

ATTORNEY Patented June .18,1940

UNITED sTATEs PATENT` ori-ice Y 2,204,808 l j MAGNET vanvE nEvrcE Donald L. McNeal, .warmem-g, ra., signor to The Westinghouse Air Brake Company, Wils merding, VPa., a corporation of Pennsylvania Anuman apra 18, 19:8, seria No. 202.582 a p s mmm. (ci. 13s- 430i This' invention relates to magnet valve devices and has particular relation to magnet valve devices for controlling uid -at high pressures.

Valve devices koperated by electromagnet coils" or solenoids and `referred to herein as magnet valve devices have certain inherent limitations when employed in the control of fluid at high pressures. If the electromagnet winding or sole-` valve devices illustrated in Figs. l, 2 and 3 may nold of the valve device is to be maintained relatively small in size, the magnetic force which may be exerted thereby isv correspondingly limited. Where the force ofthe solenoid lis employed to cause movement of a valve in direct'opposition to the pressure ofthe fluid to be controlled, the fluid pressure which the valve may successfully control is correspondingly limited. v0n theother hand.

if the electromagnet winding or solenoid of thev n\valve is designed to carry relatively high 'electri-l pressures with a minimum of electrical power'.

consumption' for operating the valve device.

Another object of my invention V is to provide` magnet valve devices-of the type indicated in the, foregoing object, adapted to operate singly or in pairs in the control of fluid under pressure.

' The above objects, andother objects of my invention which will be made apparent V'hereinafter, are obtained by'means ofillustrative embodimentsfofmy invention subsequently to be described and shown, in the ccompanying drawing, wherein:

Figs. 1, 2 'and 3 are vertical sectional views, showing respectively three different types of magnet valves embodying my invention,

Figs. 4, 5 and 6 are diagrammatic views, showing the manner in which the several magnet be employed, respectively. and

Fig. 7 is a fragmental sectional `view, 'showing a modiedv lconstruction for any of the magnet valves shown in Figs. 1, 2 and 3.

Referring to Fig. l a magnet valve device 'I3 is shown comprising asectionallzed tubular casing having a so-called magnet section' II, an interstem 34 of thevalve 32.

' The length of the tluted valves 3 I and 32 is such as t'o cause the valves 3I aii- 32 to seat mediate or piston section I2, and a lower or main valve section I3, suitablysecured together by means not shown.

Contained in-a chamber Il in the magnet section-II, which is constantly open to atmosphere through a port |5, is an electromagnet 'windingor solenoid I6 suitably ixed in insulated relation to the casing and effective when enersized to actuate a plunger I'I downwardly.

Formed in the casing section I2 is a bore I3 -in which a piston I! operates, the-pistonhaving a hollow stem 2| which extends through a passage or bore 22 of reduced diameter into a chamber 23 formed in the casing section I3. Removably secured to the end of the piston stem 2I in the annular gasket 25 on one face thereof adapted and arrangedto engage infseated relation on an annular rib seat 21 formed on the casing section I3 at the lower endo! bore-22.'

Fluid under pressure is supplied to the chamber 23 throughan inlet pipe 28 and, when the main supplyvalve 25 is unseated from the rib -seat.2'|, fluid under pressure-flows into the passage'22 to which an otlet pipe 29 is connected. j l Twooppositely seating pilot valves 3| and 32,

ilh'istr'atedl as of-the poppet type having iluted` stems 33 and 34 respectively are provided, the.

valve 3I being contained in the chamber Il of the casing section II and seating downwardly on the chamber 23 of the casing sectiony` I3 and seating upwardly on an associated valve seat 33 formed at the lower end of the stem 2I of the Apiston I9. A bore or passage 35 extends longi tudinally through the piston I9 and its stem 2l, and the ilutedstem 34 of the valve 32 extends upwardly throughvthe bore 3l into a chamber coil spring 4I, interposed between the valve 32 and a cover plate l2 which closes the chamber its associated valve seat 35 formed on the casing l section vI I, and the valve 32 being contained 4in 35-formed at the upper side ofthe piston Il. A

Y The nuted stem u or the valvesl operates slidably in a bore l5 'connecting the chamber Il in the casing section II to the chamber 35 above the piston I3 and engages the end ofthe valve 22 is'seated, thehvalv'e 2| is unseated; and

when the valve 2| is seated on its associatedseat 22, the valve 22 is unseated. Y

The lower end of the plunger 'Il engages the upper face of the valve 2| in the chamber Il and, when shifted downwardly in .response to energization of the solenoid or electromgnet winding it, shifts the valves 2| and 22 simultaneously to seated and unseated positions,

respectively. When the 'solenoid l2 is deenersized, the Spring 4| returns-the valves 2| and 22.

to unseated 'and seated positions, respectively.

In operation, with the solenoidA II deenergized, the spring 4| seats the pilot valve 22 on the main supply valve 2i and unseats the pilot valve 2|, thereby connecting the chamber 22 above the piston i2 through the bore Il to chamber VI4 and thence to atmosphere `through the -port It.;

Accordingly, with fluid under pressure supplied into the inlet pipe 2l, the main valve 2i is seated and maintained seated by the `-pressure of the fluid in the chamber 22 as well as by the torce oi' the spring 4|. L

- when the solenoid 1s enermedl and the not valves 2| and 22 shifted downwardly to seated and unseated positions respectively, fluid under pressure supplied into the chamber 22 ows past the unseated pilot valve 22 through the bore 22in thestem2| of thepiston-Iltothechamber 'above the piston I2. Since the pilot valve 2| is seated, the pressure of the uid is connned to the chamber 22 and. exerts a force urging the pistonls'downwardly into engagement -with a stop shoulder on casing section I2 to unseat the -main valve 25,- `When the main valve 2l is uniiuid under pressure flows from theinlet pipe,22 through the chamber 22 into 22 and out through the outlet pipe 29.

The chamberl 42. at the lower face of the piston .|2isopentothepassage22 throughaport 24'ina guide bushing 22 for the piston 'stem 2|. Thus, assuming that the solenoid I2 is maintained energized, the opposing iluid pressure forces on the piston I9 are ultimately balanced; The piston il thus remains in engagement with the'stop shoulder and the unseated.

When the solenoid it is deenergized and the main. supplyj valve -25 remains magnetic force urging the plunger il downwardly is accordingly relieved, the spring 4| becomes effective to shift 'the valves 2| and 22 upwardly unseated pilot valve 2|, through the chamber |4- and exhaust port I5 and the pressure of the fluid acting in chamber l2 on the lower face of the piston immediately shifts the piston 2 upwardly and causes the mainsupply valve 25 to return to seated relation on its seat-21Ito close oif the con-` nection between the inlet pipe 22 the' outlet.

the release of fluid under pressure from a reseri. voir', pipe or other receiver, two of the met* f pipe 29.

If it is desired to control both the supply valve devices Ill may be employedln combination, as mustrated 1n Fig. 4. As indicated in nsf-4.

im the solenoids of the two magnet valve devices Il are'energized by c t supplied from a source,`

thee` such as a battery Il, under the control of correl sponding switch devices Il; One of the magnet valve devices controls the supply of iluid under pressure from a source, such as a reservoir i2, to l a. control pipe l2 while the other magnet valve device controls the release of fluid under pressure from the control pipe" to atmosphere. Thus,

' with the switch 2| for the supply magnet valve open and that forthe release magnet valve closed, ,as shown, control pipe 52 is vented to. atmosphere.

In order to charge the control pipe with iiuid under pressure the switch' for the release magnet valve .is opened and that for the supply magnet is closed.Ay

In order to accurately obtain desired pressure in the control pipe u., a choke element having a restricted passage l2 therein may be provided, as shown in Fig. 7, to restrict the rate ot flow of iluld under pressure from thelnlet pipe 22n into the chamber 22 of the magnet valve device.l The rate of variation of pressure in the control pipe I2 shown yin Fig. 4 is thus restricted so as tc-enable the control `oi' the magnet valve devices Il by the switches 5| to establish a desired pressure in control pipe 52. l i

It will be apparent that'the magnet valve de'- vics. i2 are adapted to control fluid at relatively high pressures while maintaining the size of the solenoid relatively small, becausev the solenoid need bey only of suillcient size to exert a force suillcient to4 overcome the combined force ot spring 4| and the force of the iluid pressure in the chamber' 22 acting on the face of the ,pilot valve 42. Since the actual size of the pilot valve 22maycorrespondtothatshowninliig. 1 orbe even smaller, it-will be seen that a relatively small size solenoidis required, notwithstanding the high pressures of iluid which may be controlled by the main valve 2l.' v

' Referring to Fig. 2, a magnet valve device It of modified form to um ofltne magnet valve device Il is shown. Magnet valve device 2l differs from the magnet valve device I2 essentially in the arrangement' of the valve parts in such manner that the solenoid corresponding to the solenoid Il must be energized in order to cause seating of the main supply valve 2l as distinguishedA from the magnet valve device II where the solenoid j must be deenergiced to cause seatingof the valve covers' I2 and Il at opposite ends thereof secured .u

to the sections 6| and t2 respectively.

Formed in the casing section 6| is a chamber Vhaving an inlet pipe 2l connected theretol and containing a solenoidv (not shown) similaqto the solenoid I6 oi' the magnet valve Il, and an associated plunger I1. J Also formed in. the casing section Bl isa chamber 22 to which an outlet pipe 2s is connected, the two chambers 26 and 68 being separated by a wall-having a bore or passag/ 'H therein connectingthe two chambers. To 65 on' the wall 22 surroundingjthe'passage 1| and within the chamber 2l is an vannular rib septy 'l2 fon'which the main supply valve 2l is adapted t0 seat toclose communication between tb; chambers 82 and 22.

The lowercasing section 22 has formd therein a bore 12 in whichjthe piston I2 for operating the mainvalve2liscontained,thestm2| ofthe piston being guided slidably in a bushing 1l, ilxed in the :over wan u enne-canne neuen u. wdff;

I stricted port 83`isV relatively small compared to extending through the chamber 88 and passage 1I to the chamber 66 where the main vsupply valve 25 is secured thereto. l, I

The wall 15 of the casing section 6I contains a. port 18 whichiconnects the chamber 68 with a chamber 11 at the upper side of the piston I9 within the casing section 62. i

A wall 19 of the casing section 62 is located between the piston I9 and the end cover so as to form a chamber 8| between the lower face of the piston I9 and the wall 19, and a chamber 82 between the wall-u and the end cover '64. The chamber 8| is constantly connected to the chamber 82, through-fa restricted port 83 in the ,wall

19 and 'the chamber 82 is constantly'open to atl mosphere through an exhaust port 89.

A pilot valve 85 of the poppet type is contained inthe chamber 66 andarranged so as to be shifted downwardly by the plungerI1 into seated'relation on'ian associated valve .seat 86,

formed on the end of the piston stem 2| withinl the chamber 66'. The pilot valve 85 has a fluted stem 8 1 which is slidably guided in a longitudinal bore 88 in the stern 2| of the piston I9. A stem 89 having a flut'ed upper portion and a smooth' lower portion is contained in the bore 88 in the piston. stem 2| and extends downwardly through a circular opening 9| in the wall -19 into the chamber 82. The smooth portion of the stem 89 fits closely in the opening 9| to prevent appreciable leakage of fluid under pressure from the Ychamber 8| tothe chamber 82 along the stem 89.

Fixed to the lower end of the stem 89 within the chamber 82 is a collar or flange 92. A'coil spring 93, interposed between the collar 92 and end ccver 64, yieldinglyurges the stem 89 upwardly untilstopped by the engagement of the collar 92 with the wall 19. The upper end of the stern 89 engagesthe lower end of the fluted stem 81 of the pilot valve 85 withinthe longitudinal bore 88 of the piston stem 2| and, when the solenoid associated with the plunger I1 is deenergized, the spring 93 urges the stem 89 upwardly to reflect unseating ofthe pilot valve 85 from its valve seat 86. When the solenoid of the magnet ,valve 68 is energized, the force of the plunger I1 on the pilot valve 85 shifts it downwardly into seated position against the yielding resistance of the spring 93.

In operation, when the solenoid of the magnet valve I6 is energized and the plunger I1 actuated downwardly to seat the pilot valve 85, the supply of'fiuid under pressure from the inlet pipe 28 and chamber 66 throughthe longitudinal passage 88 of the piston stem 2| to the'chamber 8| beneath the piston I9 is cut off and, accordingly, the pressure in chamber 8| is reduced to atmospheric pressurefby flowvof the fluid in the chamber through the restricted port 8 8, chamber 82 and vexhaust port 84. kThe piston I9 and main valve 25 accordingly move downwardly until the main valve 25 seats on the annular rib seat 12 at which time the pressure of the iluid inthe chamber 66 as well as the magnetic force on plunger I1 is effective to maintain the valve 25 seated. With the main valve 2 5 seated; the connection between the inlet pipe 28 and the outlet pipe 29 is closed.

under pressure from the chamber 66 flows past the unseated valve 85 through the longitudinal passage 88 in piston stem'2ly to the chamber 8| beneath the piston 4I9. The ow area' of re- `ward fluid pressure force on the main .valve 25,-

the piston I9 is shifted upwarlyto effect unseating of the main valve 25. The engagement of the upper face of the piston I9 with the lwall 15 limits the unseating movement of the main supply valve 25 to an amount which is insuflicient to y reseat the pilot valve 85 and thus the communication from the chamber 66' to the chamber 8l remains open past the pilot valve 85 when the main valve 25 isfunSeated.

With the main supply valve 25 unseated, flui under pressure is supplied from the inlet pipe 28 and chamber 86 through the passage 1| to the chamber 68 and outlet pipe 29, the pressure of the'fluid in the chamber 68 being effective, through the port 16, in chamber 11 on the upper face of the piston I9.

Since fluid under pressure is exhausted /through port 83 from chamber A8| at a restricted rate, the pressure built up in chamber 8 I 4is maintained and .thus iiuid` under pressure continues to be supplied 'past' the unseated main supply valve 25 until the solenoid is energized or until the pressure in the outlet pipe 29 equalizes with that in the inlet pipe 28. When the solenoid is energized and the plunger I1 actuated downwardly to reseat the pilot valve 85 onits seat 86, the connection between the chamber |56` and the chamber 8| is closed and consequently the. fluid under vUpon the reduction of the pressure in the" y chamber 8|, the pressure of the fluid in chamber -11' above the piston I9 is effective to urge the piston downwardly and thereby reseat the main supply' valve 25 to close the connection betwee the inletv pipe 28 and outlet pipe 29.

Ilteferring to Fig. 5, the manner in which a pair ofcfmagnet valve devices 68 may be employed to 'control the supply and the release of fluid under "pressure from a control pipe is indicated. As in the arrangement'shown in Fig; 4 for magnet valveilllj, the ysolenoids of the magnet valve 88 are, arranged to be energized by current supplied fromaybattery 58 lunder the`control of corresponding kswitches 5I. As shown, the switch 5I for"'=the magnet valve 60 controlling the supply of fluidA .under pressure from tlerreservoir 52 to .thercontrol pipe 53 is closed so that the solenoid isenergized andthe supply of uid under pres-- sure from the reservoir to the pipe 53 cut olf.

At 'the same time, the switch 5| for the second magnet valve 60 is in open position so that the solenoid'of `the second magnet valve is deenergized' and thereby conditioned to release fluid under -pressurefrom the pipe 53 to atmosphere.'

l--If it is desired to establish a certain pressure in pipe 53, switch 5I for the release magnet valve is rst closed toA cut oif the release communication for the pipe 53 and then the switch 5I for the ,supplyr magnet valve is opened, thereby effectingoperation of the supply magnet valve to cause liiuld under pressure to flow from the res- Aent and guided in the bore ||,5.

ervoir 52 to the pipe 53. When the desired pressure is established in the pipe 53, switch 5| for the supply magnet valve is reclosed and the further supply to the pipe 53 cut off.

As in the case of magnet valve I0, the magnet valves of Fig. 5 may be provided with a choke element 55 in the passage between the inlet pipe 20 and the chamber 55 to restrict supply of fluid under pressure past the main valve 25 suillciently to enable graduated control of the pressure in the pipe 53.

Referring to Fig. 3, a magnet valve device |00 is shown which embodies the fundamental principles of my invention and which diil'ers from the magnet valves I0 and 50 in performing both supply and release functions in a single unit instead of requiring two units as is the case with the magnet valves l0 and 60. The magnet valve |00 is suited particularly to those' applications in which either iull pressure or atmospheric pressure is required, there being no need for graduated or intermediate pressure.

'I'he casing of the magnet valve |00 is tubular in shape and comprises 'an upper magnet section |0|, a lower valve section |02, and an intermediate section |03, together with end covers |00 and for the sections |0| and |02, respectively.

Formed in the magnet section |0| is a chamber |01 in which is contained a solenoid, correspending tol solenoid I6, for actuating a plunger The intermediate casing section |03 has formed therein a chamber |00 which is constantly open to atmosphere through an exhaust port |09.

The valve section |02 of the casing has formed in the lower end thereof a chamber which is closed 'by the end cov'er |05, to which chamber the inlet pipe is connected. Another chamber ||2. to which the outlet pipe 20 is connected, is formed in the casing section 02 and is open to the chamber through a bore 3. Opening out of the opposite side of the chamber ||2 in axial relation to the bore ||3 is a bore ||5 which opens into a bore ||0 of larger diameter than the bore ||5.

A pistonl valve ||0 operates in the bore 0 and has a portion of reduced diameter iluted longitudinally for al purpose hereinafter made appar- 'I'he piston valve ||0 is formed as a poppet valve so that when moved downwardly it seats on a conical valve zsat ||0 formed between theA two bores ||0 and The piston valve ||0 is normally unseated upwardly from the valve seat ||0 'and a plurality of ports |2| at spaced intervals around the casing section. |02 open into the bore 0 beneath the piston. It will thus be apparent that when the passage ||3 into the chamber and a main piston valve- |.|0 is raised from the valve seat |10, the chamber ||2 is connected to atmosphere through the ports |2| and the longitudinal grooves on the iluted reduced portion of the Piston.

The piston valve ||0 has astem |23 which ex` tends downwardly through the chamber 2 and supply valve`25, corresponding to the main supply valve of the magnet valve devices |0 ,and 00,

is removably secured thereon within the chamber A,fluted collar or flange |25 formed on the stem |23is guided slidably in the bore ||3 in the casing. Y -1 Formed on the lower end of the stem |23 is a valve seat |25 on which a pilot valve |21 o! the poppet type is adapted to seat. A coil spring a wall |33 of the intermediate casing section |03.

Contained in the chamber |00 of the casing section |03 is a poppet valve |30 which has a fiuted stem |35 that extends through a circular opening |36 in the wall |33 into the chamber |32 and engages the upper end of the iluted stem |29 of the pilot valve |21. Formed on the wall v|33 in surrounding relation to the opening |35 is a valve seat |31 on which the valve |30 seats when shifted downwardly. The fluted"'stems |20 and |35 of the valve |21 and |30`are of such lengths as to cause the valves |21 and |30 to seat oppositely. I'hat is, when the pilot valve |21 is seated the valve is unseated, andA vice versa.

Formed in a wall |30 of the casing section |0| is a circular opening |33 which4 connects the chamber |01 to the chamber |00. A flanged disk-like stop member |0| is slidably movable in the opening |30, and a coil spring |02 interposed between the valve |30 and stop member |0| is eiective to urge the stop member |0| upwardly until the ange on the stop member engages the walll30. 'Ihe spring |02 is of such length or strength as not to prevent unseating of the valve |30 by the spring |20.

V travel is not required, the spring |02 and stop |0| may be omitted and the plunger |1 may then directly engage the valve 30.

A simple application of the magnet valve |00 is indicated in Fig. 6, wherein the solenoid of the magnet valve is energized by current supplied from a battery. under the control of a switch 5|, the inlet pipe 20 being connected to a source otgiiuid under pressure, such as a reservoir 52;

and the outlet pipe 20 being connected to a control pipe 53. y

In operation, with the solenoid of the magnet valve device |00 deenergized. the pilot valves |21 and |30 are seated and unseated, respectively, and the piston valve 0 and'main supply valve 25 are raised to unseated and seated positions, respectively. Accordingly, the supply of fluid under pressure from the reservoir 52 is cut off by `the main supply valve 25 and the control'pipe 53 and outlet pipe 20 leading .thereto are vented to atmosphere through the exhaust ports |2|.

When the solenoid of the magnet valve 00 is energized, the pilot valves |21 and I 30 are shifted to unseated and seated positions, respectively.

With the pilot valve |30 seated, the connection between the chamber |32 and the atmospheric 'port |03 is cut oi! and with the pilot valve |21 l aaoaeos chamber |32 increases sufficiently the piston valve ||9 is' shifted downwardly into seated relation on its valve seat ||9 and simultaneously unseats the main supply valve 25. With the piston valve ||9 seated on the valve seat ||9, the exhaust communication from the outlet pipe 29 to atmosphere through the exhaust ports |2| is seated, iluid under pressurexis supplied therepast through the passage ||3; and' chamber ||2 to the outlet pipe 29 and control pipe 53. A

As previously explained, the magnet valve |99 is intended primarily as an on-and-off device and, consequently, y the solenoid is f maintained energized until the full lor maximum pressure is attained in the control pipe 53. The area of the piston valve ||9 subject to the pressure of the iluid in chamber |32 is iarg'erthan the area of the piston valvesubject to the pressure of the uid in the chamber ||2 and, consequently, the piston valve ||9 is-maintained 'seated o'n the valve seat ||9 'by the diierential of the uid pressure forces in the chambers |32 and 2,

I When the solenoid ofthe magnet valvex |90 is subsequently deenergized, the pilot valves |2'lnand |34 are shifted upwardly, to seatedand unseated positions, respectively. It will be observed that the downward movement of the piston valve ||8 into seated relationon its valve seat |'|9 is less than the amount of movementof the pilot valves |2`| and |34 relative to their associated valve seats, and consequently when the] pilot valve |21' is shifted upwardly into seated relation on the stem |23 of the piston Valve ||9 while the piston valve ||9 seated on its valve seat ||9, the pilot valve |34 is unseated. -O

When the pilot vvalve |34 is unseated, the' chamber. |32 is vented to atmosphere by way of chamber. |99 and exhaust port |99 and, consequently, the pressure of the fluid in the chamber ||2 becomes-effective to shift the piston valve. 9 upwardly away from its'valve seat ll9'and thereby returns the mainA supply valve 25 to seated position, Thus, communication from the supply reservoir 5 2 to the outlet pip'e 29 is cut off and the exhaust communication from the outlet pipe 29 to atmosphere through the exhaust ports |2| is established. Obviously, once the main supply valve 25 is seated, it is thereafter maintained seated, untily the solenoid isv energized, by the force of the uid pressure acting in chamber assisted by the force of the spring |28, which force isA greater than the combined weight of the piston valve H9, stem |23 and the valve 25.

summarizing, it will be s eenfthat I have disclosed a plurality of types of magnet valve de- -vices embodying my invention, each of the types shown being provided with a relatively small sized solenoid consuming a relatively small amount of power but adapted to eif'ectoperation of the magnety valve devices to handle fluid at relatively high pressure. v-

It will be understoodthat while I vhave shown only several speciiic embodiments of my invention, various omissions, additions or modifications may be made in the embodiments shown without departing from the spirit of my' invention. It is accordingly not my intention tolimit the scope of my inventionI except as,it'is necessitated by the scope'of the priorart Having now described my invention. what I claim as new and desire to secure byl Letters Patent, is:

l. A magnet valve device comprising a casing sure o! the iiuid in the rst said chamber, a third chamber, a movable abutment subject on one side to the fluid pressure in thesaid second chamber and on the opposite side to the pressure-of the :duid in said third chamber, valve means for controlling the supply of uid under pressure from the rst said chamber to the said third chamber to cause said movable abutment to operate to unseat the said valve and for controlling the release of uid under pressure from the said third chamber for 'causing said abutment lto operate to seat said valve in response to the vpressure of the iluid in said second chamber, and a' solenoid for eecting operation of 'said valve means. l a

2. A magnet valve device comprising a casing having a chamber constantly connected to a source of iluid pressure,asecond chamber to which an outlet passage is connected, a valve controlling' communication between the first and second'chambers, a third chamber, a movable abutment ysubject on one side toithepressure of the uidin the said secondlchamber and on the opposite side to the pressure in said third chamber, said movable abutment having a passage therein through which uid under pressure may be supplied from the iirst said chamber to the said third chamber, a pair of oppositely seating pilot valves one of which oontrolsvthe supply lof chamber and the other of which controls the release of fluid under pressure from the said Ythird chamber, anda solenoid eiective'when energized to operate the said pilot valves so as to cause an increase'in pressure in the said third chamber and consequent shifting of the movable abutment to effect unseating of the said valve and effective when ldeenergized to operate the said pilot valvesto eilectv the release ofuid under pressure from the said third chamber Awhereby the said movable abutment is actuated by the pressure of thefluid in the said second chamber to eifect seating of the said valve.

3. A magnet valve device comprising a casing having a iirst chamber constantly connected to av source of iluidpressure, a second chamber to which an outlet passage is constantly connected, a pairof oppositely seating main valves oneof which is contained in the said first chamber and controls communication between the-rstand second chambers and the other of which controls r .rst and secondchambers and'to cause .unseating of the said othe/x` main valve to open communication from 'the second chamberto atmosphere, uuid pressure lresponsive means for opl erating said main valves, pilot valve means for controlling the supply and the release of uid under pressure to control the pressure of iiuid acting on the iluid pressure responsive means,

and a solenoid for eilecting operation of .said pilot valve means. L l

4. A magnet valve device comprising a casing having a iirst chamber constantly connected to a source oi' ilu'id pressure, a .second chamber to which an outlet passage is connected, a pair of oppositel'y seating main valves. one of which is contained in the said iirst chamber and maintained in seated position to close communication between the saidiirst and second chambers by the pressure oi the duid in said first chamber, the other o1' said main valves being simultaneously unseated to establish arr-exhaust communication from said second chamber to atmosphere, a third chamber, a movable abutment i'or operating said main valves subject on one side over a certain area to the pressure oi/uid insaid third chamber and subjecton the opposite side over a lesser area to the pressure oi' uid in the said second chamber. said movable abutment being ef- 's'ective whensubject to the pressure of iiuid in said third chamber to operate the said one. and the other of` the main valves to unseuted and seated positions respectively and eii'ective to maintain said main valves in such position by the diderential of the ligdmpressure forces acting on opposite sides thereo otwithstanding equalization oi the iluid pressure on opposite sides thereof, pilot valveJmoans controlling the supply and l" the release o! iiuid underpressure toand from said third chamber, and a solenoid for eiiecting operation oi said pilot valve means.

5. A magnet valve device comprising a casing having a chamber connected to a source o! iluid under pressure, a second chamber towhich an outlet passage is connected. a third chamber, a movable abutment carrying two oppositely seating valves one o! which is contained in the said first chamber to control communication between the iirst chamber and the second chamber and the other of which is arranged to control communication between the second chamber and atmosphere, said movable abutment having a passage' therein through which iiuid under pressure may'iiow from the said irst chamber to the said third chamber, a first pilot valve arranged to control communication through the said passage to admit uid under pressure from the iirst chamber to the third chamber, a second pilot valve arranged to release iluid under pressure from the said third chamber, said movable abutment being shifted in a direction to unseat said one valve and seat the other of said valves upon the supply of iiuid under pressure to the said third chamber and shifted in the opposite direction to seat said one valve and unseat the other of said valves upon the release of iiuid under pressure from said third chamber, and a solenoid 4for enacting operation of said pilot valves to control the pressure in the said third chamber.

. DONALD McNEAL. 

